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© 2006 IBM Corporation AFP Color Consortium

AFP Color Management Architecture (ACMA) Overview – XPLOR 2006

Reinhard Hohensee, IBMJean Aschenbrenner, IBMJohn Meixel, IBM

2 AFP Color Consortium

AgendaOverview – Reinhard Hohensee

What is the AFP Color Consortium (AFPCC) and what are its goals?ICC Profiles and Color Management Resources (CMRs)CMRs in MO:DCA (AFP) data

Color Management Resources (CMRs) – Jean AschenbrennerColor Management Object Content Architecture (CMOCA)CMR types and structureCMRs in IPDS data

AFP Color Management Tools and Utilities – John MeixelCMR Installer and the CMR Resource Access Table (RAT)CMR Engine (CMRE)Data Object Installer and the Data Object RATCMR Usage scenarios

SummaryQ & A


AFP Color Consortium

Formed in October 2004Goal is to develop a comprehensive color management capability within the AFP architecture

Customers demand accurate colors regardless of output device• Customers demand consistent colors across multi-vendor configurations

and workflows• To protect significant color investment, products must be based on open

standards• Many companies provide AFP products, need broad buy-in to have an

industry-wide solution

First release of architecture was formally approved January 20, 2006 and will now be publishedFor more information, see afpcolor.org


Current AFP Color Consortium Membership (27)

Document Composition & Resource Creation:

• Cincom• COPI• DocuCorp• Document Sciences• Elixir Technologies• Exstream Software• GMC Software Technology• Group 1• Inventive Designers• Isis-Papyrus• Metavante• PrintSoft• StreamServe

Servers & Transforms• CDP Communications • Compart Systemhaus• Crawford Technologies• Emtex• MPI• Solimar Systems• Xenos Group Inc.

Printers & Controllers• IBM• Intermate• Kodak• Lexmark• Oce• Xeikon International• Xerox


Goals of AFP Color Management (contd)

Accurate output color if input color properly defined

Standards-based (ICC), open architecture

Consistent output color and grayscale simulation on different devices driven by different applications

AFPPrinter

inputprofile printer

profile

RGBCMYK....

CMYK

AFPPrinter (x)

AFPPrinter (y)input

profile

printer (y)profile

printer (x)profileRGB

CMYK....

CMYK (y)

CMYK (x)


Goals of AFP Color Management (contd)

Tunable output color

High-speed output color

AFPPrinter

halftone(y)

halftone(x)


ICC ProfilesThe International Color Consortium (ICC) was formed in the early 1990s to address the problem of color management in printers, displays, scanners, operating systems, applications, servers, in an open, industry-standard manner. This work resulted in the ICC Specification, which defines methods for color management that are based on objects called ICC profiles.ICC profiles are created for input and output devices by their manufacturer and are essentially look-up-tables (LUTs) that specify how to convert between the color space of the device, e.g. a specific RGB for a display (input color), or a specific CMYK for a printer (output color), and a standard device-independent color space called the Profile Connection Space (PCS). The color spaces used for the PCS are CIE Lab and CIE XYZ.This conversion to/from PCS via ICC profiles allows colors to beaccurately passed from input devices to output devices.


ICC Profiles – System View

Scanner XICC Profile

Display ZICC Profile

Printer BICC ProfilePrinter A

ICC Profile

Scanner X

Display Z

Printer A Printer B

L = 48a = -12b = -22

(Rx,Gx,Bx)

(Rz,Gz,Bz)

(Cb,Mb,Yb,Kb)(Ca,Ma,Ya,Ka)

AFP

AFP

AFPAFP

Lab value of blue isL = 48a = -12b = -22

Profile ConnectionSpace (PCS)


The AFP Color Management Resource (CMR)

ICC profiles are the industry-standard for color management and form the basis for color management in AFP; they are integrated into AFP as resources that are called AFP Color Management Resources (CMRs)

• AFP CMRs are:• Defined in a new formal architecture under the AFP Architecture umbrella –

the Color Management Object Content Architecture (CMOCA)• Processed as AFP resources – installed, downloaded, activated, captured,

re-used • Can be associated with a MO:DCA document component:

• Printfile• Document• Group of pages/sheets• Page or overlay• Data object


CMR TypesColor Conversion (CC) CMRs: Contain ICC profiles (in their ICC-defined syntax) that convert a device-specific color to/from the device-independent ICC Profile Connection Space (PCS)

Tone Transfer Curve (TTC) CMRs: Transfer curves that are used to modify the values of a particular color component

Halftone (HT) CMRs: Screens that are applied to multi-bit data

Indexed (IX) CMRs: Mappings of indexed colors in the data stream to output device colors or colorant combinations

Link Color Conversion (LK) CMRs: Look-up tables (LUTs) that convert directly from a device-specific input color space in the data to the device-specific output color space of the presentation device


CMR Processing Modes

Audit: An audit CMR specifies color-management processing that has been done on a document component; for example, it may specify a color conversion that has been done on the dataInstruction: An instruction CMR specifies color-management processing that is to be done on a document component; for example, it may specify a halftone that is to be applied to multi-bit dataLink: A link CMR is used to link an input color space in the presentation data directly to the output color space of the presentation device (without going through the PCS)

The processing mode is not part of the CMR; it is specified in the context in which the CMR is associated with a document component, e.g., on the structured field that references the CMR.


CMR Creation and Installation: CMR Installer and CMRE

CMRs are installed as resources in an AFP resource library with a workstation-based CMR Installer that is part of a new Resource Installer. The CMR Installer:

uploads the CMR into the resource library of a print serverbuilds the CMR Resource Access Table (RAT) entry that maps the CMR name to a file name, to an object-OID, and optionally to other CMRs

CMRs are created by the CMR Engine (CMRE), which runs in conjunction with the Resource Installer to:

Generate Color Conversion (CC) CMRs from ICC profiles, including profiles that were copied/extracted from data objectsGenerate Halftone (HT), Tone Transfer Curve (TTC), and Indexed (IX) CMRs from input dataGenerate Link Color Conversion (LK) CMRs that convert the input color space defined in an audit CC CMR to the output color space of configured presentation devices


Inline CMRs

CMRs may also be carried in a printfile-level resource group in a BRS -BOC/EOC – ERS container, and are then called inline CMRs

BRS specifies CMR nameFor inline Color Conversion CMRs, BRS may specify Link Color Conversion CMRsthat convert directly to output color spaces of different target devicesFor inline generic Halftone or Tone Transfer Curve CMRs, BRS may specify device-specific HT or TTC CMRs; such CMRs are used in place of the inline generic CMR if the device type and model match the target device


Associating CMRs with a MO:DCA document component

CMRs can be associated with document components at all levels of theMO:DCA document hierarchy:

Printfile (highest)DocumentGroup of pages/sheetsPage/overlayData object (lowest)

A CMR at a lower level always overrides – for that document component only – a conflicting CMR at a higher level

Example: CC CMR at printfile level defines RGB = scanner (y) RGB, CC CMR at page (n) level defines RGB = scanner (x) RGB. According to rule, since CC CMRs conflict, all RGB for page (n) is interpreted as scanner (x) RGB


Example: Associating CMRs with a Document Component: Printfile

BFM (FormDef)

BDG (Document Environment Group (DEG))

.................

MDR, CMRname = cmrxyz

X’10’ triplet: Object-type OID = CMR

X’91’ triplet: Processing mode = audit

..................

EDG

....................

EFM

ResourceLibrary

PrinterCache

Controller PRTPrintServer

CMRRAT

AFP(MO:DCA-P)Printfile

IPDS

cmrxyz

CapturedCMRs

*** CMR scope = complete printfile ***


Associating CMRs with a MO:DCA document component (Cont’d)

A similar method can be used to associate CMRs with a single document in the printfile by specifying the offset to the document in the printfileCMRs can be associated with a group of pages/sheets by referencing the CMRs in a Medium Map; the scope of the CMRsis then the group of pages/sheets that followCMRs can be associated with a page or overlay by referencing the CMRs in the Active Environment Group (AEG) if the page/overlayCMRs can be associated with a data object, such as an IOCA FS45 color image, in a number of ways:

By referencing the CMRs in the Object Environment Group (OEG) of the data object


Associating CMRs with a MO:DCA document component (Cont’d)

By referencing the CMRs on the Include Object (IOB) structured field that places the data object on the page/overlay

Data objects may be installed by a component of the Resource Installer called the Data Object Installer. This installer builds a Data Object Resource Access Table (RAT) that maps the object name to a file name, to an object OID, and optionally to one or more CMRs. This provides a method for associating CMRswith a data object that does not require any changes to the object or the data stream that references the object.


User Input: Rendering IntentThe ICC defines four rendering intents to specify how out-of-gamut colors should be mapped to in-gamut colors; each may produce a different output appearance:

Perceptual: Tries to preserve appearance by maintaining color relationships; typically used to render continuous-tone images Saturation: Tries to generate vivid, saturated colors, even at the expense of color accuracy; typically used for business graphicsMedia-relative colorimetric: Maps white point of source color to white point of output media; colors ‘look right’ but may not be accurate colorimetrically. Typically used for vector graphics or images.ICC-absolute colorimetric: Does not map white point of source color to white point of output media. If source white is bluish and media white is yellowish, system adds cyan to simulate blue on output medium. Colors are accurate colorimetrically but may not ‘look right’. Typically used for logos or proofing.

To properly process Color Conversion CMRs and Link Color Conversion CMRs, the system needs to know the end user’s rendering intent


Rendering Intent (Cont’d)

End users can associate rendering intent with MO:DCA document components at the same levels of the document hierarchy as CMRs

Specified with a Rendering Intent (RI) triplet:• In the DEG of the FormDef to specify RI for the printfile or for a specific

document in the printfile• In the AEG of a page or overlay to specify RI for that page/overlay• In the OEG of a data object to specify RI for the data object• On an IOB to specify RI for the included object• On a PPO to specify RI for an object to be preprocessed

Can also be associated with a data object in the Data Object RATSpecified independently for each major AFP object-type category

• IOCA• Object containers (EPS/PDF/TIFF/JFIF/GIF)• PTOCA• GOCA


CMR Architecture

ACMA AFP Color Management ArchitectureDeveloped by AFP Color Consortium w/ IBM’s leadershipAdditions to MO:DCA, IPDS, IOCA …CMOCA: new tower in AFPWhite Paper: draft is available at www.afpcolor.org

CMOCA Color Management Object Content ArchitectureDefines CMRs - Color Management ResourcesDocuments how CMRs are usedCMR is an AFP resource; carried in an Object ContainerSpecification coming soon to www.afpcolor.org


CMR Structure

CMR data (tag format)CMRDataN

headerCMRHeader164

DescriptionNameLength (bytes)


CMR Structure - CMR Header

Set to zeroReserved8

Used to reference the CMR in data stream(UTF-16BE format)

CMRName146


CMRDataN

Signature for CMR typeEye-catcher stringX’434D5239’ CMR9

CMRSig4

CMR lengthLength4



CMR Structure - CMR Name

Reserved8

Human-readable nameCMR Alias16

Reserved2

CMRDataN

Set to “@...@”Reserved16

CMR-type-specific fields46

Media-specific fields22

Device-specific fields 28

Version of this CMRCMR VersionOr ‘generic’

14

CMR Type: HT, TTC, CC, LK, IXCMR Type4

CMRSig4

Length4



CMR Structure : CMRDataAll CMR data is carried in CMR tags

Each type of CMR tag has an IDCMR tags are specified in ascending order of IDTag has header and dataAll tags (headers) occur first in the CMR data fieldTag data follows

Tags used depend on the CMR type:HalftoneCalibration CurveColor ConversionIndexedLink Color Conversion


CMR Structure – Tag Syntax

if <4 bytes: Data, left aligned else: offset to data from byte 164

Value/Offset4

Number of values of indicated field type

Count4

Data format of fieldFieldType1


Unique identifier for tagTagID2



Going from Input to Output with CMRs

Color ConversionInput (e.g. RGB) PCS Output (e.g. CMYK)

Tone Transfer Curve : calibration1-D for each color plane

Halftone (each color plane)

Indexed CMRs : maps index to color components Will be discussed later


CMR Type: Color Conversion (CC) CMR

TIFF image24 bit RGBscanner x

Printer bit map32 bit CMYKInfocolor 130+

ICC Profile ConnectionSpace (PCS) - CIELab D50or CIEXYZ D50 (24 bit)

CC CMR: scanner xICC profile -RGB --> PCS

CC CMR: Infocolor 130+ICC profile -PCS --> CMYK

Processing mode = audit Processing mode = instruction


CMR Type: Tone Transfer Curve (TTC) CMRTone Transfer Curve Data Tag -

Cyan Component

C (in) C (out)

0

1

2

............

95 102

255

1

1

3

250

256 entries foreach of the 256possible inputvalues(0 to 255)

4 tables total if output color space is CMYK


CMR Type: Halftone (HT) CMR

Page pixel grid

Bilevel Point-OperationScreen Data Tag -Cyan component

Cellheight (m)

Cell width (n)

T00 T0n

Tm0 Tmn

.........

.........

.

.

.

.

.

.

...

xxxxxxxx

Threshold array forn x m halftone cell

Halftone cells are superimposed on pixel grid;if pixel value corresponding to Tij is less than Tij,output pixel = B’0’, otherwise it is B’1’


CMR Type: Link Color Conversion (LK) CMR

Look-up tables (LUTs) that convert directly from the input color space of the data to the output color space of the presentation device

Improves performance since Links avoid conversion to/from PCSFormally associates an audit Color Conversion CMR with an instruction Color Conversion CMR by specifying the object OIDs for each CMREach Link CMR actually contains 4 LUTs

one for each rendering intent

Transparent to end-user; not referenced in data stream


Link Color Conversions (contd)

TIFF image24 bit RGBscanner x

Printer bit map32 bit CMYKInfocolor 130+

LK CMR:scanner x RGB ->Infocolor 130+ CMYK

Processing mode = link


CMR Type: Indexed (IX) CMR

Color Specified = Highlight Color Space (X’4E’ triplet format) X’0000’ – X’00FF’ spot colorX’0100’ – X’FFFF’ resolve with Indexed CMR

Indexed CMR tells how to create output given the index

Different types of tags:CMYK Tag: Index values CMYK valuesGray Tag: Index values grayscale valuesNamed Colorant Tag: Index values combinations of named colorantsAll tags: Index values CIELAB values

• Used if device does not support the selected color space


Indexed CMR: Named Colorant Tag

………………..…………………………

Intensity of nth colorant………….

Intensity of 2nd colorant

Intensity of 1st colorantCIELAB valueID = X’xxxx’………………………………..…………..


Indexed CMR: Colorant Identification Tag

Length Colorant n Name

………. ……………………

Length Colorant 2 Name

Length Colorant 1 Name


Generic CMRs

Instruction CMRs provide a mechanism whereby the output can be tuned to a specific output device.

Generic (instruction) CMRs provide a mechanism whereby the output can be tuned consistently across different devices.

Use generic CMRs to request an intended output appearance.


Generic CMRs (contd)

Generic Halftone CMR examples:71 lpi (clustered dot)85 lpi (clustered dot)106 lpi (clustered dot)StochasticError diffusion

Generic Tone Transfer Curve examples:DarkAccutoneHighlight MidtoneStandard


Generic CMRs (contd)Only Halftone and Tone Transfer Curve CMRs can be specified as generic CMRs.

Generic CMRs are identified with the fixed character pattern “generic” in the version field of the CMR name

All generic CMRs are registered in the CMR Architecture Spec.

Generic CMRs are never used directly by an output deviceThey are always replaced by device-specific CMRs

Done by the print server based on a device-specific CMR mapping in the CMR RAT orDone by the output device


IPDS Considerations

CMRs are activated/deactivated like all other resourcesPrinter selects CMRs using the following hierarchy:

Data-object levelPage overlay levelPage levelHomestate level (printfile, document-level, and page/sheet group level CMRs)

Default level

Invoking CMRsAudit and instruction CMRs must be explicitly invokedNew Invoke CMR command for homestate-level invocationNew Invoke CMR triplet for object-level invocationLink CMRS need not be invoked


CMR Resource Access Table (RAT)

When CMRs are installed in resource libraries, they are processed using a CMR Resource Access Table (RAT)

RAT concept first introduced in AFP with TrueType/OpenType fontsArchitected structure defined in the MO:DCA reference (SC31-6802)

Allows CMRs to be referenced in data stream by their inherent, native name, not by a platform-specific file name

Data stream is platform-independentMapping to platform-specific file name, to object-OID, and to other processing information accomplished via RAT

CMR RAT is located in same library as CMRsRAT consists of repeating groups (RGs)

One repeating group for each CMR in libraryRepeating group is indexed with CMR name from data stream

RAT


RAT Processing to Find TrueType Font

1. Job specifies “Arial” font2. Print Server looks in RAT

contained in path /u/meixelspecified by:1. Job FONTPATH parameter2. Print Server FONTPATH parameterRAT has reserved name of:

IBM_DataObjectFont.rat

3. Print Server finds RAT entry for font name “Arial”

4. Arial RAT entry point to TrueType file name of “arial.ttf”

5. Print Server downloads “arial.ttf”to printer

RATarial.ttf

/u/meixel

PrintServer

MDR = ArialFONTPATH = ‘/u/meixel’

FONTPATH = ‘/u/meixel’


TrueType Font Specified in Application File

Map Data Resource, MDR Data-Object Font Descriptor

Fully Qualified Name “Arial”


RAT Processing to Find TrueType Font

EUID=888613003 /u/meixel/ Type Filename _ Dir . _ Dir .. _ File arial.ttf_ File IBM_DataObjectFont.rat

FONTPATH = '/u/meixel'

Full Font Name(internal applicationname): “Arial”

Font File Name(external): “arial.ttf”

Font Resource Directory “/u/meixel”Application or Print Server

Fontpath Parameter

RAT


CMR Installer

CMRs are installed as resources in an AFP resource libraryThe CMR Installer is part of a new workstation Resource Installer The CMR Installer:

uploads the CMR into the resource library of a print serverbuilds the CMR Resource Access Table (RAT) entry that maps the CMR name to a file name, to an object-OID, and possibly to one or more device-specific CMRs


CMRs – System View

CMRResource

Library

ICC ProfilesHalftones

Tone Transfer CurvesIndexed Color Mappings

CMRsRAT

CMR Installer

AFP Generator Print Server Printer Control Unit

Color AFP Files +CMR References


Data Object Installer

Copies TIFF, JPEG, GIF, FS45, and other color object files, to the Data Object resource library without modificationAdds entry to Data Object RAT to associate internal application object name, (object-OID), with the object’s external file nameBuilds Color Conversion CMRs for Data Objects that contain embedded ICC profilesOptionally builds a Compacted Data Object, by removing the embedded ICC profile, to improve object download performance


Data Objects – System View

Data ObjectResource

Library

TIFFJPEGGIF

FS45

DataObjects

RAT

Data Object Installer

AFP Generator Print Server Printer Control Unit

Color AFP Files +Data Object References


CMR Usage Scenarios

“What’s the least amount of work I need to do to get accurate and consistent colors?”“I like my output with saturated colors; can I tune the data stream to achieve this regardless of where I print?”“I’m very picky and am not afraid of AFP structured fields - can I control the whole process?”


Usage scenario: least amount of work

Ensure that every device-dependent color in the printfile is properly defined using audit CC CMRs

If all colors created by same device, e.g. same scanner or same digital camera, need only associate the CC CMR for that device at the printfile-level in the FormDef (as an audit CMR)If differently-sourced colors at different levels of the hierarchy, need to associate appropriate CC CMRs as audit CMRs with those document components

Don’t specify instruction CMRs – let the output device select the appropriate defaults


Usage scenario – tuned, consistent output

Reference generic instruction TTC/HT CMRs in data stream; outputdevices will make reasonably consistent adjustment to the output.Example: Specify following generic CMRs as instruction CMRs for printfile in

FormDef:Generic HT CMR = 106 lpiGeneric TTC CMR = Highlight Midtone

Each output device will apply device-specific CMRs that simulate the requested output appearance


Usage scenario – control it all

Ensure that every device-dependent color in the printfile is properly defined using audit CC CMRs

If all colors created by same device, e.g. same scanner or same digital camera, need only associate the CC CMR for that device at the printfile-level in the FormDef (as an audit CMR)If differently-sourced colors at different levels of the hierarchy, need to associate appropriate CC CMRs as audit CMRs with those document components

Specify instruction CC, HT, and TTC CMRs for the printfileUse device-specific HT and TTC CMRs tuned for the output deviceTune CC, HT, and TTC CMRs for the specific output media


Summary: AFP Color Management SystemCMR

Installer

AFP GeneratorApplication

CMR Engine(CMRE)

CMR Engine(CMRE)

CMR Engine(CMRE)

ObjectInstaller

ICC Profiles

TIFF/JPEG/GIF

Halftones

Indexed colormappings

EPS/PDF

Tone Transfercurves

FS45.....

CMRResourceLibrary

DataObject

ResourceLibrary

Color AFP files +CMR references

PrintServer

CMRRAT

Data ObjectRAT

Accurate,Consistent,

TuneableColors andGrayscales

PrinterController

- creates CMRs- builds link CMRs

- creates CMRsfrom copied/extracted profiles

- createslink CMRs

- maps CMR names tofile names & OIDs

- points to link CMRs

- installs CMRs- builds CMR RAT

- installs data objects& compacted objects

- builds DO RAT- copies/extractsprofiles

- maps object namesto file names & OIDs

- associates CMRswith objects

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